The present invention pertains to a four-way manual seat adjuster and in particular to a clutch assembly for holding a seat in position after it has been adjusted in the vertical direction.
Conventional vehicle seat assemblies are manually adjustable in the fore and aft direction to accommodate occupants of various sizes. A six way power adjustable seat is also available in which the seat can be raised and lowered and pivoted forward and rearward about a lower rear axis in addition to being adjustable fore and aft. A power adjustable seat however, requires a relatively complex adjustment mechanism and one or more electric motors.
Four way adjustable seats have recently been developed that provide for a manual adjustment to raise and lower the seat in addition to the typical fore and aft adjustment. However, the operating controls for many four way manually adjustable seats have an relatively cumbersome to use. For example, one mechanism includes an operating lever that is raised and lowered to move the seat and is laterally deflected to engage a pin extending from the operating lever in and out of selected openings in an adjacent frame to hold the seat in place. It may be difficult, when the seat is loaded, to disengage the pin from the frame to make an adjustment and furthermore, the mechanism only provides fixed adjustment positions rather than infinite adjustment.
It is an object of the present invention to provide a clutch assembly for use in a four way manual seat adjuster to hold the seat in position and which is simple in operation and provides infinite seat adjustment.
The seat adjuster includes two torque tubes extending laterally between opposite sides of the seat assembly. The torque tubes are pivotally connected to the upper sliding rails of the seat assembly for fore and aft movement. A bell crank is coupled to the forward torsion tube and a link is pivotally coupled at one end to the bell crank and to the rear torsion tube through a crank arm enabling both torsion tubes to rotate in unison. A riser plate is also pivotally connected to the bell crank at its forward end and connected to the rear torsion tube through a second crank arm at its rear end. Rotation of the torsion tubes will raise or lower the riser plate. The seat cushion and seat back are carried by the riser plate for vertical motion.
The clutch assembly of this invention is used to hold the front torsion tube stationary and prevent its rotation. The clutch assembly includes a cylindrical housing which is concentric about the forward torsion tube and fixed to the sliding rail to hold it stationary. The clutch assembly includes two coil clutch springs having a relaxed diameter slightly less than the inside diameter of the housing. A biasing means engages the ends of the springs, forcing the springs to expand radially outward to frictionally engage the clutch housing to prevent rotation of the clutch springs. The forward torsion tube is also coupled to the springs to prevent rotation of the torsion tube when the clutch springs are frictionally engaging the housing.
An operating handle for the clutch assembly includes a shaft portion parallel to the forward torsion tube and a handle portion extending generally radially from the shaft portion. The shaft portion rotates about the longitudinal axis of the torsion tube and releases the clutch spring biasing means to enable the torsion tube to rotate in the direction of rotation of the handle thus raising or lowering the seat assembly.
Further objects, features and advantages of the invention will become apparent from a consideration of the following description and the appended claims when taken in connection with the accompanying drawings.